Which results in less error?

[NiCKEL]

If I want to react iron nails and different concentrations of acid, should I choose 1 nail for a certain concentration and keep the nail throughout 3 trials or should I switch every single time? The nails are already used to start with; so switching nails has the disadvantage of not knowing what it previously reacted with, but using the same nail means it will constantly get worn down, so will that affect rate of reaction? Which one's the best, I need to make the best out of the situation.

[IB_taking_over]

Are you measuring the change in weight after the reaction?

 

If so, I would suggest that you clean the nails to remove the outer coating before each trial (steel wool is pretty good as this). That way you have a clean surface with each trial. The biggest source of error with this method would be the slight change in surface area, but I don't believe it will make a huge difference.

 

Hope this helps

[NiCKEL]

Are you measuring the change in weight after the reaction?

 

If so, I would suggest that you clean the nails to remove the outer coating before each trial (steel wool is pretty good as this). That way you have a clean surface with each trial. The biggest source of error with this method would be the slight change in surface area, but I don't believe it will make a huge difference.

 

Hope this helps

I was actually going to measure the Fe ions in the acid after reaction by titration. You don't think the surface area change will matter much, so that means using the same nail (5 nails for 5 concentrations of acid, 1 for each conc.) is ok right? just to clarify

[IB_taking_over]

Yeah, the surface area shouldn't matter.

Five nails for five concentrations should work.